This invention relates to a coupling apparatus for a speed regulator, or governor, particularly of a type used in motor vehicles. The invention relates even more particularly to such a coupling apparatus having parts which move with respect to one another but which can be selectively affixed to one another so that a governor positioning drive is effectively linked to a speed adjusting apparatus for controlling, directly or indirectly a motor throttle.
A coupling apparatus of the type of this invention is disclosed in German Gebrauchsmuster No. GM 77 35 209. The coupling apparatus, which is between a speed adjustment apparatus for controlling the operation of an internal combustion engine and a governor positioning drive, comprises two parts which are moveable relative to one another and a third, or fastening, part, which connects the first two parts together. The fastening part includes a latch mounted on one of the first two parts which is driven by an electromagnet to engage a depression in the other part. The first part is cylindrically shaped and can be coupled directly to a gas-pedal lever. The second part is a piston that is slidable inside a cylindrical bore of the first part. The latch is mounted on the outer surface of the cylinder of the first part and the depression is in the piston of the second part. The piston is connected via a toothed rod with a positioning motor. When the governor is not being used the speed adjustment apparatus should be decoupled from the governor positioning drive. Should the governor be activated, the latch is driven by the electromagnet through an opening in the cylinder of the first part into the surface of the piston. The governor positioning drive moves the piston out of a neutral position so long as the latch is pressing into the depression of the piston, and this is controlled by a switch. Thus, the driving speed is controlled by the governor. If the governor is turned off by means of the switch, the bolt is lifted out of the depression by a return spring once the electromagnet is deenergized so that the vehicle speed is once again determined by a driver. It is disadvantageous to employ a latch that is driven by an electromagnet and returned by a spring inasmuch as such an arrangement is not simple and is not inexpensive. Also, one must have a switch which shows the position of the latch. Also, it is disadvantageous that the latch presses on an outer surface of the piston when the governor is activated and then rides along the piston until it falls into the depression, which involves a delay in operation of the governor and tends to create undue wear on the parts. Still further, it is disadvantageous that when a driver wishes to accelerate he must first overcome the resistance of the latch in order to decouple the first and second parts.
German Gebrauchsmuster No. GM 78 08 547 discloses a coupling assembly which has a pneumatic positioning element at one end of a coupling rod whose movement is transmitted over the coupling rod. A coupling apparatus, at an opposite end of the coupling rod, is coupled to the coupling rod via an adjustment apparatus. The coupling apparatus in this case is a ball socket. A disadvantage of this arrangement is that decoupling of the positioning element from the speed adjusting apparatus, which is coupled to the coupling apparatus, is not provided so that every movement of the positioning element is passed on to the speed adjustment apparatus. Thus, the force needed to move the speed adjustment apparatus is increased as is the wear and tear on the speed adjustment apparatus. Also, it is disadvantageous that with this arrangement the adjustment apparatus comprises a threaded shaft with a nut with which a fine, exact, and quick adjustment of the coupling apparatus to a basic position of the speed adjustment apparatus is only possible with difficulty, since tightening the nut creates a force in the speed adjusting apparatus.
It is an object of this invention to provide a coupling apparatus which is uncomplicated and inexpensive to both produce and mount. It is also an object of this invention to provide a coupling apparatus which works well with most speed adjustment apparatus. Further, it is an object of this invention to provide a coupling apparatus for a speed governor in which a governor positioning drive can be decoupled from a speed adjusting apparatus without application of additional force to manually move the speed adjustment apparatus.